Several methods are known in the art for joining portions of hollow organs, such as the gastrointestinal tract. These include threads for manual suturing, staplers for mechanical suturing, and compression rings and clips.
While manual suturing is universally known and relatively inexpensive, the degree of success depends considerably on the skill of the surgeon. Another disadvantage is that post-operative complications are common. Further, suturing an organ results in lack of smoothness of the tissue therein, which, when the sutured organ is part of the gastrointestinal tract, hampers peristalsis in the sutured area. Finally, suturing is both labor and time consuming.
Staplers for mechanical suturing ensure a reliable joining of tissue and enable the time needed for surgery to be reduced, compared with manual suturing. However, due to the facts that such staples are not reusable and that a great many types and sizes are required, the price of staples is high. Also, after healing, metal staples remain in place along the perimeter of the suture, which reduces elasticity of the junction and adversely affects peristalsis when the sutured organ is part of the gastrointestinal tract.
Junctions using compression devices such as rings and clips ensure the best seal and post-operative functioning of the organs. Two types of compression devices are known, namely, rings made of resorption plastics and clips made of memory alloys. Plastic rings are cumbersome and expensive. Also, the compression force is applied only momentarily at the junction and is reduced as the tissue is crushed. Clips made of memory alloys enable portions of tissue to be pressed together with increasing pressure as they are heated, due to the inherent properties of the alloys.
Development of clips made of memory alloy materials has increased recently, as they have many advantages over other devices. Their design is simple, they are cheap, they are small in size and possess universal qualities, and they are self-evacuated from the gastrointestinal tract.
It is known in the art to provide a surgical fastening clip which applies a clamping force to a site, such as a blood vessel, thereby reducing its cross-sectional area. It is also known to provide a surgical fastening clip formed of a shape memory alloy which deforms to a closed configuration when heated, such that the clamping force applied thereby is increased as it is heated. For example, U.S. Pat. No. 5,171,252 discloses a surgical fastening clip formed of a shape memory alloy; the device disclosed therein includes separate legs which close tightly around a site. Such a device is limited in its uses, such as for clamping blood vessels, and is not suitable for joining portions of the gastrointestinal tract.
EP 0,326,757 discloses a device for anastomosing a digestive tract, which includes a plurality of U-shaped retaining clips disposed around a soluble support tube. The tube is positioned inside portions of the digestive tract to be joined, and includes an outer groove around which are disposed the U-shaped retaining clips. The retaining clips are made of a shape memory alloy such that the open ends thereof close at a predetermined temperature, thus joining ends of the digestive tract. Once the ends of the digestive tract have been joined, the tube is dissolved. Such a device is disadvantageous in that its use requires that a plurality of clips to be properly positioned simultaneously. Also, there is no assurance that the resulting junction will be smooth, due to the plurality of sites of the digestive tract joined by the plurality of clips.
SU 1,186,199 discloses a memory alloy clip consisting of two parallel coils to be used for joining portions of a hollow organ, such as an organ of the gastrointestinal tract. The portions of the organ to be joined are aligned, and each of the plastic coils is introduced through a puncture formed in the wall of one of the portions. The coils are positioned such that, when heated, they compress the aligned walls therebetween, thus maintaining the portions of the walls held within the loops of the coils adjacent each other. Thereafter, incisions are made through the portions of the walls held within the loops of the coils, such that a passageway is created between the two organ portions. The punctures in the organ walls must then be surgically sewn closed with interrupted surgical sutures.
A major disadvantage of known memory alloy clips is that they permit compression of only approximately 80-85% of the junction perimeter, thus requiring additional manual sutures, which reduce the seal of the junction during the healing period and its elasticity during the post-operative period. Furthermore, this additional suturing is problematic inasmuch as it has to carried out across a joint which includes a portion of the clip, thereby rendering difficult the sealing and anastomosis of the organ portions.